Introducer devices for introducing intravenously a stent, stent graft or other implant or prosthesis are typically provided with an outer sheath within which there is provided a deployment mechanism such as a pusher rod and dilator. The sheath has the function of containing the various components of the introducer device and in particular the implant therewithin during the intraluminal introduction procedure. This flexes and twists as it passes through the various lumens of the patient, until it reaches the location at which the device being carried needs to be implanted. The sheath is typically of a construction that it is flexible so can be passed relatively easily through lumens of a patient and yet is able to withstand rotational torque, which is important during the implant placement process, for example for rotating the implant at the implantation site to ensure that it is implanted in the correct orientation. For this purpose, the sheath is of a length that extends, normally, to a dilator tip at the distal end of the introducer device and also to outside the insertion site in the patient, for example to outside the femoral artery. This end is typically termed the proximal end. This proximal end of the sheath typically has fitted integral therewith a plurality of manipulation elements for controlling the introduction of the sheath into the patient, the release of the implant, as well as for supplying various fluids during the medical procedure, such as saline solution or necessary medicaments.
Typically, the implant is located at the end of a pusher rod, which is itself flexible, which extends from the proximal to the distal ends of the deployment device and within the sheath.
It is necessary for the implantation procedure to be able to lock the pusher rod and the sheath together and a number of devices have been disclosed in the past.
For example, U.S. Pat. No. 5,064,414 discloses a locking clip which is clipped both to the pusher and to one of the grasping tabs of the sheath, the grasping tabs forming a handle for use by the surgeon. This locking unit limits the longitudinal movement of the pusher rod relative to the sheath until it is unlocked. However, the locking unit allows for rotation of the pusher relative to the sheath and some axial movement of the proximal end of the pusher relative to the proximal end of the sheath.